Checked this a bit and looks quite good for the early state of things (ignoring the known todos). Not sure about the naming "drag all selected" though. Not really descriptive and could be misunderstood. Esp. don't see what it has to do with dragging? How about "affect all selected"?

The patch is now finished (in that it works with multi-drag now, also support Alt+LMB number button editing).

Sweet! Now, nobody can say the UI gets no love :) Thank you for polishing Blender Campbell !

Talked with @Ton Roosendaal (ton) on this and he's OK to have this committed to master, as first step, (having the feature working on basic level it is now),

Then get exact details sorted out by UI team.

Issues that should be eventually resolved.

• Some visual indication this feature is being use.
• Possibly some indication in properties header, eg:
  
  Scene -> "Some" object
  
  to ...
  
  Scene -> "Some" object (+ 5 selected)
• Ensure some kind of predictable behavior when in local-view or using unlocked layers.
  
  (probably OR the layer mask of all View3D's in the visible windows areas)
• Exactly how to enable, as noted already.

Design task for this created here: https://developer.blender.org/T44666

Clear operators (Alt R, Alt G, Alt S...) have no XYZ checkboxes.
The only way to reset only one value of an array to 0 is to manually enter the value in properties or to use the reset value to default values operator.

But here, Alt+clicking to enter a 0 value will not reset values of all selected objects to zero.
It will change values of selected objects according to offset between initial value of active object and 0.

It looks like multi-objects ediiting does not work with backspace or ctrl backspace.

Is it possible to make Alt Ctrl Backspace resetting the value for all selected objects ?

I rather agree with Ton here, first commit the code with the basics, then take time to really discuss the best shortcuts. In the meantime, basics are better than nothing and people can make a custom shortcut they like anyway.